"As a law enforcement officer you ... are responsible for enforcing the laws, not determining if they are constitutional," Costello said. When asked if he would enforce gun reform laws, Cannon answered, "probably ... yes," and added, "but I will look closely at my own understanding of the constitution, my own study, and will put that in the context of what ... others say."

He compared his role to that of a military officer, who he said does not have to follow "unlawful orders."

Costello is one of CNN's more outspoken anchors. She kicked a guest off her show after he spewed anti-gay hatred on the air. She also urged conservative members of the media, including Rush Limbaugh and the Drudge Report, to "step back from the edge" of the gun control debate.